JP2004197028A - Aqueous adhesive composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a polychloroprene latex adhesive composition for an aqueous adhesive which is excellent in adhesion performance such as initial adhesive strength and dry adhesive strength, and can be used for an applicator such as a roll coater where an adhesive undergoes intermittent shear and exposure to air. <P>SOLUTION: This bonding method excellent in initial adhesion characteristics and applicable to an applicator other than a spray applicator such as a roll coater where a latex adhesive undergoes a big mechanical/chemical load comprises (a) adjusting pH of an anionic chloroprene latex containing sodium hydroxide and/or potassium hydroxide obtained by polymerization at a temperature of 30°C or above using a rosin acid-based emulsifier, (b) using in combination two kinds of additives having a water retention property and (c) executing a press-joining in a wet state. The aqueous adhesive composition has as an essential component (A) an anionic chloroprene latex, (B) a tackiness-imparting resin and/or a dibasic acid ester-based plasticizer and/or a softener, (C) a pH modifier capable of adjusting a latex pH to 7-10, (D) a moisture-retaining agent of water-soluble glycols and/or ureas and (E) a viscosity enhancer having a water retention property of an acrylic copolymer or a polyacrylic acid type. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

【００３２】
【発明の効果】
従来、限定された塗布方法において水系接着剤の遅乾燥を補う方法が提示されてきたが、本発明となる水性接着剤組成物は、ロール安定性及び初期接着強度に極めて優れ、エアースプレーガン以外の塗布方法を選定することが可能となる。このため従来の水系接着剤では使用できなかったロールコーター等の使用が出来るようになることにより、接着剤ロスを大幅に削減し、ミスト状飛散物の発生を無くすることが可能であり、合板など木材接着、紙材、家具、布などの接着に特に好適なポリクロロプレンラテックス接着剤組成物を提供することが出来る。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a polychloroprene latex composition-based adhesive composition effective as an adhesive. More specifically, it is excellent in adhesive performance such as initial adhesive strength and normal adhesive strength, and can be used in a coating machine such as a roll coater exposed to intermittent shear or air contact, and is suitable as a water-based contact adhesive. The present invention relates to a polychloroprene latex-based adhesive composition.
[0002]
[Prior art]
Conventionally, adhesives based on polychloroprene have been mainly of the solvent type. However, in recent years, there has been an increasing demand for solvent-based adhesives to be desolvated due to problems such as hygiene, danger of fire, and environmental pollution due to organic solvents during production and use.
[0003]
As a method of desolvation, a method of replacing a solvent-type adhesive with a latex adhesive is considered to be effective, and latex adhesives using various polymers have been actively studied.
[0004]
Above all, the polychloroprene latex adhesive is applied to both adherends to be bonded, and after drying these adhesive layers, they are bonded to each other, so that a high adhesive strength is immediately exhibited. Because of these characteristics, it is expected to be used as a water-based contact adhesive, but the adhesive performance of the initial adhesive strength is inferior to that of a solvent-based adhesive, and this improvement has been a subject.
[0005]
For example, JP-A-4-298536 and JP-A-11-286668 disclose a method for producing a spray adhesive by adjusting the pH of an anionic chloroprene latex with an amphoteric compound such as glycine or a weak acid such as boric acid. However, with such an adhesive, the mechanical stability of the adhesive is extremely poor, and it cannot withstand the intermittent share of the adhesive or air contact. It could only be applied by a method that could form a film after contact. If the adhesive is to be applied by a roll coater, an adhesive coagulated film is formed several tens of seconds after the adhesive is supplied, and the bonding operation cannot be performed.
[0006]
When applying a latex-based adhesive by spraying, since the latex particles are so fine that the adhesive discharged from the nozzle of the air spray gun is scattered due to air resistance, the discharge of the adhesive adhered to the adherend after the spray gun is discharged. Adhesion efficiency is about 60%, and adhesive loss is large, and wasteful use of adhesive is increased, suction to the human body by scattered adhesive, dirt around the workplace, and the like are obstructive factors for desolvation.
[0007]
[Patent Document 1]
JP-A-50-22084
[Patent Document 2]
JP-A-4-298536
[Patent Document 3]
JP-A-6-287360
[Patent Document 4]
JP-A-10-195406
[Patent Document 5]
JP-A-11-286668
[0008]
[Problems to be solved by the invention]
The present invention solves such problems of the prior art, and is excellent in adhesive performance such as initial adhesive strength and normal adhesive strength, and is applied to a roll coater or the like which is exposed to an intermittent share of an adhesive or air contact. An object of the present invention is to provide a polychloroprene latex composition for an aqueous adhesive which can be used in a machine, a method for producing the same, and an adhesive composition using the same.
[0009]
[Means for Solving the Problems]
The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, for example, natural rosins such as gum rosin, tall oil rosin, wood rosin, disproportionated rosin, hydroxide rosin, polymerized rosin, α, β- Using a modified rosin such as a modified rosin such as an ethylenically unsaturated carboxylic acid modified rosin, a purified product of the natural rosin, a rosin acid emulsifier such as a product of the modified rosin, and polymerizing at a temperature of 30 ° C. or more. By adjusting the pH of the anionic chloroprene latex containing sodium hydroxide and / or potassium hydroxide obtained by the above method, and further using a combination of two types of additives having water retention, by pressure bonding in a wet state. Excellent in initial bonding performance and large mechanical / chemical load on latex adhesive, using coating equipment other than spray coating equipment such as roll coater Apply found adhering methods are possible, thereby completing the present invention.
[0010]
That is, the present invention provides (A) an anionic chloroprene latex, (B) a tackifier resin and / or a dibasic ester plasticizer and / or a softener, and (C) a pH adjuster capable of adjusting the latex to 7 to 10. , (D) water-soluble glycols and / or ureas humectants, (E) water-retentive acrylic copolymers, or polyacrylic acid-based thickeners (A) to (E) And an aqueous adhesive composition containing, as an essential component.
[0011]
Hereinafter, the present invention will be described in detail. The chloroprene polymer in the present invention may be a homopolymer of 2-chloro-1,3-butadiene (hereinafter, referred to as chloroprene) or one or more other monomers copolymerizable with chloroprene, and an emulsifier for rosin acids may be used as an alkali. An anionic chloroprene latex obtained by polymerization in the presence of a polymer having a property of improving mechanical and chemical stability at a pH of 12 or more.
[0012]
Examples of the monomer copolymerizable with chloroprene in the present invention include 2,3-dichloro-1,3-butadiene, 1-chloro-1,3-butadiene, butadiene, isoprene, styrene, acrylonitrile, acrylic acid and the like. Examples thereof include esters, methacrylic acid and esters thereof, and if necessary, two or more of these may be used.
[0013]
In the chloroprene latex adhesive of the present invention, it is necessary to add a pH adjuster to the chloroprene latex to adjust the latex PH to 7 to 10. As such a pH adjuster, in addition to common acidic substances such as inorganic acids and organic acids and their amphoteric compounds such as amino acids, emulsions having a pH of 10 or less and various latexes may be used. And one or more of these can be used in combination. For example, organic acids include acetic acid, formic acid, glycolic acid, malic acid, citric acid, maleic acid, fumaric acid, malonic acid, phthalic acid, isophthalic acid, lactic acid, butyric acid, ascorbic acid, succinic acid, tartaric acid, acrylic acid, Examples include methacrylic acid, crotonic acid, adipic acid, oxalic acid, abietic acid, and the like.Examples of inorganic acids include boric acid, phosphoric acid, hydrochloric acid, nitric acid, nitrous acid, sulfuric acid, and sulfurous acid. And salts with sodium, potassium, ammonia, aminoethanol, diethanolamine and triethanolamine. Examples of the amino acids include glycine, glycylglycine, asparagine, aspartic acid, alanine, phenylalanine, arginine, glutamine, glutamic acid, and the like.As the emulsion having a pH of 10 or less, a copolymer emulsion of an acrylic ester or a methacrylic ester is used. And a styrene-butadiene copolymer obtained by copolymerizing acrylic acid, methacrylic acid and the like, and a carboxyl-modified synthetic rubber latex such as chloroprene, but are not particularly limited thereto. In terms of adhesion performance and latex stability, amino acids such as glycine, alanine, phenylalanine, and glutamic acid, and organic acids such as malonic acid are preferable.
[0014]
The humectants used in the present invention are polyhydric alcohols, glycols and ureas. Examples of the tackifying resin include rosin resin, rosin ester resin, hydrogenated rosin resin, polymerized rosin resin, α-pinene resin, β-pinene resin, terpene phenol resin, C5 fraction petroleum resin, C9 fraction petroleum resin, C5 Fraction / C9 fraction petroleum resin, DCPD petroleum resin, alkylphenol resin, xylene resin, coumarone resin, coumarone indene resin and other tackifying resins can be added. As a method of adding the tackifier resin, it is preferable to add the resin in the form of an emulsion in order to uniformly disperse the resin in the adhesive composition. Depending on the required characteristics of the application at the time of use, other metal oxides such as zinc oxide, dibasic acid ester-based plasticizers or softeners such as dibutyl sebacate and process oil, as well as various antioxidants and vulcanization accelerators And a curing agent such as an isocyanate.
[0015]
In the present invention, an acrylic copolymer having a humectant and a water retention agent used to impart suitability for a coating machine such as a roll coater, or a polyacrylic acid-based thickener is an essential component and has a water retention property. Water retention agents to be used are polyhydric alcohols, glycols, urea and the like.
[0016]
According to the bonding method of the present invention, the same or different types of bonding such as paper, wood, cloth, leather, leather, rubber, plastic, foam, pottery, glass, ceramic, and metal can be favorably performed. Excellent in adhesiveness. Further, in the bonding method of the present invention, when at least one side is made of a porous organic material such as paper, wood, cloth, leather, leather, foam, etc., a higher bonding performance is obtained, and the porous organic materials having good porous properties are obtained. A laminate of a porous organic material and a non-porous material can be obtained. Regarding the method of applying the latex adhesive, in the case of an anionic chloroprene latex adhesive whose pH has been adjusted, in general, it can be applied only by air spray application because a coagulate is generated by an instantaneous share, but this adhesive is intermittent. Since the liquid can be maintained without generating a coagulated product even when exposed to an excessive shear or air contact, brush coating, iron coating, spray coating, roll coater coating and the like are possible.
[0017]
As a method of applying the adhesive, a conventionally known roll coater, air spray, or the like can be used. Further, a method of applying and bonding to both surfaces of each adherend to be bonded or a method of applying and bonding only to one side is also possible. The amount of application is preferably about 30 to 200 g / m ² as an adhesive on the surface of the adherend, more preferably about 40 to 150 g / m ² , and further about 1 to 10 minutes after application. Crimping is preferred.
[0018]
Furthermore, when an adhesive is applied, a higher initial adhesiveness can be exhibited by using an aqueous solution of a metal salt as a coagulant. As a method of applying the coagulant, a method of applying the chloroprene latex adhesive and then applying it on the adhesive layer using another spray, or conversely, applying the coagulant first and then applying the chloroprene latex adhesive And the like. Examples of the coagulant include aqueous solutions such as sodium chloride, potassium chloride, calcium chloride, magnesium chloride, aluminum chloride, sodium sulfate, potassium sulfate, magnesium sulfate, aluminum sulfate, sodium nitrate, potassium nitrate, calcium nitrate, magnesium nitrate, and aluminum nitrate. However, the present invention is not limited to this.
[0019]
The adhesive composition of the present invention is prepared by mixing a polychloroprene latex, a tackifier resin, a pH adjuster, and a moisturizer, but the mixing device is not particularly limited, and a known device such as a three-one motor may be used. Can be used.
[0020]
The polychloroprene latex adhesive obtained according to the present invention is suitable for bonding the same or different types of paper, wood, cloth, leather, leather, rubber, plastic, foam, pottery, glass, ceramic, metal and the like. . Regarding the application method at the time of bonding, brush application, iron application, spray application, roll coater application and the like are possible.
[0021]
【Example】
Hereinafter, the present invention will be described specifically with reference to Examples, but these Examples do not limit the present invention. In the following examples, parts and percentages are by weight unless otherwise specified.
[0022]
After the preparation of the aqueous adhesive composition, the following measurements were performed.
[PH measurement] After adjusting the latex sample to 20 ° C in a thermostatic water bath, the pH was measured with a PH meter.
[Storage stability test] A latex sample was allowed to stand at 40 ° C for 2 months in an environmental tester set at 40 ° C, and examined for any change in the adhesive state such as generation of a coagulated product. (○: no change, ×: change)
[Spray application stability] Using an air spray gun with a diameter of 2.0 mm, the number of times of clogging of the gun when applying with a maximum discharge amount for 5 minutes is measured. (○: 0 times, Δ: 1 time, ×: 2 times or more)
[Roll coating stability] The prepared latex sample was put into a roll coater coating machine set so that the doctor roll was 7 m / min, the applicator roll was 20 m / min, and the coating amount on the urethane foam was 100 g / m ² . The state change one hour after idling was measured.
(○: adhesive keeps liquid, ×: solidified on roll)
[Initial adhesion] Latex samples prepared a roll coater and coated at a coverage of 100 g / m ² to urethane foam, and pressed immediately bonding the coated surfaces are, in sense of resistance when the attempts to force destruction immediately after The adhesion was determined. (○: strong ← resistance → weak: ×)
[0023]
Embodiment 1
Anionic chloroprene latex C-84 (manufactured by Bayer AG), rosin ester aqueous dispersion superester E-720 (manufactured by Arakawa Chemical Industry Co., Ltd.) as a tackifying resin for 100 parts of a solid content of 55%, PH of 12.0 or more. , 50% solids, 20 parts PH 8.0, 5 parts dibutyl phthalate as a plasticizer / softener, 1 part urea as a humectant, 1 part urea, a thickener as an aqueous solution of an acrylic copolymer A- 818 (manufactured by San Nopco Co., Ltd.) were mixed. Further, 4 parts of glycine was added as a pH adjuster to adjust the adhesive of Example 1 having a pH of 8.8.
[0024]
Embodiment 2
Among the anionic chloroprene latex compositions prepared in Example 1, rosin ester aqueous dispersion Harristar SK-130D (manufactured by Harima Kasei Co., Ltd.), 50% solids, and PH 8.0 as tackifying resins. Except for the addition, the adhesive of Example 2 having a pH of 8.3 was prepared in the same manner as in Example 1.
[0025]
Embodiment 3
In the composition of the anionic chloroprene latex prepared in Example 1, the adhesive of Example 3 having a pH of 8.8 was prepared in the same manner as in Example 1 except that ethylene glycol was used as a humectant and 2 parts of the humectant was added.
[0026]
[Comparative Example 1]
Example 1 A nonionic chloroprene latex LC-501 (manufactured by Denki Kagaku Kogyo Co., Ltd.), a solid content of 47%, and a pH of 7.0 were added to the composition of the anionic chloroprene latex prepared in Example 1, except that 100 parts of PH 7.0 were added. In the same manner as in the above, an adhesive of Comparative Example 1 having a pH of 6.8 was prepared.
[0027]
[Comparative Example 2]
In the composition of the anionic chloroprene latex prepared in Example 1, the adhesive of Comparative Example 2 having a pH of 8.8 was prepared in the same manner as in Example 1 except that urea added as a humectant was not added. Was adjusted.
[0028]
[Comparative Example 3]
In the composition of the anionic chloroprene latex prepared in Example 1, the same procedure as in Example 1 was performed except that 3 parts of an aqueous solution of urethane resin UH-420 (manufactured by Asahi Denka Co., Ltd.) was added as a thickener. The adhesive of Comparative Example 3 having a pH of 8.8 was prepared.
[0029]
[Comparative Example 4]
In the composition of the anionic chloroprene latex prepared in Example 1, the adhesive of Comparative Example 4 having a pH of 11.5 was prepared in the same manner as in Example 1 except that glycine added as a pH adjuster was not added. Was adjusted.
[0030]
[Comparative Example 5]
In the composition of the anionic chloroprene latex prepared in Example 1, the same procedure as in Example 1 was carried out except that urea added as a humectant and A-818 added as a thickener were omitted. Thus, the adhesive of Comparative Example 5 having a pH of 8.9 was prepared.
[0031]

[0032]
【The invention's effect】
Conventionally, a method for compensating for the slow drying of the water-based adhesive in a limited coating method has been proposed. Can be selected. For this reason, it becomes possible to use a roll coater, etc., which could not be used with the conventional water-based adhesive, so that the adhesive loss can be greatly reduced, and the generation of mist-like scattered substances can be eliminated. Thus, it is possible to provide a polychloroprene latex adhesive composition particularly suitable for bonding wood, paper, furniture, cloth and the like.

Claims (1)

(A) an anionic chloroprene latex, (B) a tackifier resin and / or a dibasic ester plasticizer and / or a softener, (C) a pH adjuster capable of adjusting the latex to 7 to 10, (D) water A humectant of glycols and / or ureas soluble in water, (E) an acrylic copolymer having water retention, or a polyacrylic acid thickener (A) to (E) as essential components Aqueous adhesive composition.